JPH0245016Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention is used in serial printers that print characters, etc. on a print medium placed on a platen while the print head moves. This invention relates to a platen gap adjustment mechanism that adjusts the gap between the platen gap and the platen gap.

[Conventional technology]

The print head installed in an impact-type serial printer has a platen gap, which is the gap between the print head and the platen, determined by its responsiveness and output energy, and the platen gap is determined by the number of copies of printing paper to be used. It is necessary to adjust the amount to an appropriate amount depending on the thickness of the paper.

This conventional platen gear adjustment mechanism has
For example, there are JP-A-58-90975 and JP-A-58-175951, and the basics of these will be explained below based on the drawings.

FIG. 6 is a plan view of the conventional platen gap adjustment mechanism according to the above-mentioned publication, and FIG. 7 is a perspective view of an eccentric bush that constitutes the main part thereof.

In the figure, 1 is the print head, 2 is the carriage on which print head 1 is mounted, and 3 is the carriage 2.
4 is a hole provided eccentrically in the eccentric bush 3; 5 is a carriage 2;
6 and 7 are guide shafts that are slidably passed through the hole 4 of the eccentric bush 3 and the circular hole 5 of the carriage 2, and 8 is a guide shaft that faces the print head 1 for printing. The platens 9 and 10 forming the surfaces are frames that respectively support the guide shafts 6 and 7 and the platen 8 in parallel on both sides.

The conventional platen gap adjustment mechanism is as described above, and the carriage 2 carrying the print head 1 slides on the guide shafts 6 and 7 and moves in the direction of the arrow 11.

To adjust the platen gap between the print head 1 and the platen 8, the carriage 2 is moved in the direction of arrow 12 by rotating the eccentric bush 3.

This is done by the circular hole 5 attached to the guide shaft 7 assisting in changing the wall thickness with respect to the guide shaft 6 by rotating the eccentric bush 3 attached to the guide shaft 6. It's summery.

As described above, this platen gap is adjusted according to the number of copies and the thickness of the printing paper used.

[Problem that the invention attempts to solve]

However, since the print head 1 and the carriage 2 are composed of multiple parts, it is necessary to initialize the platen gap by taking into account the cumulative dimensional tolerances of the parts. The eccentric bushing 3 in
The phase of the printing paper varies from printer to printer and is not constant, and due to the characteristics of the eccentric bushing 3, rotation is limited to within a certain phase range in order to obtain the desired amount of change in the platen gap. When changing the platen gap depending on conditions, use the already set eccentric bushing 3.
There was a problem in that the necessary amount of change in the platen gap could not be obtained with the amount of rotation.

The present invention addresses the above problems,
The goal is to achieve a platen gap adjustment mechanism that can accommodate a large amount of adjustment.

[Means for solving problems]

Therefore, the present invention provides a platen gap adjustment mechanism that adjusts the platen gap between the print head mounted on the carriage and the platen, in which a guide rail is provided parallel to the rear of the main guide shaft arranged parallel to the platen. The front end of the carriage is slidably and rotatably attached to the
A gear switching lever having a shoe having a gear at its upper end screwed onto a carriage, a lower end of the shoe slidably abutting on the guide rail, and teeth formed on the carriage to mesh with the gear. It is characterized by being rotatably provided.

[Effect]

According to the above means, a gear that can be moved up and down at the upper end of the shoe is moved, the engagement between the gear and the platen gear switching lever is released, the shoe is freely rotated, and the length of the shoe's protrusion downward from the carriage is adjusted. This causes the carriage to rotate about the main guide shaft, thereby changing the inclination of the print head together with the carriage, thereby initializing the platen gap between the print head and the platen.

Thereafter, the gear and the gap switching lever are engaged again, and the gap switching lever rotates the shoe together with the gear, thereby obtaining the desired platen gap.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a side view thereof, and FIG. 3 is the same side view showing the initial setting of the platen gap.

In the figure, 13 is the printing head, 14 is the carriage, 15 is the main guide shaft slidably attached to the end of the carriage 14 on which the printing head 13 is mounted, and 16 is the bottom of the carriage 14, which covers the entire range of movement of the carriage 14. Base frame provided in 16
a is a guide rail in which the base frame 16 is formed close to the end opposite to the end of the carriage 14; 17 is a shoe screwed onto the carriage 14;
The lower end of this shoe 17 protrudes below the carriage 14 and comes into contact with the guide rail 16a due to the weight of the carriage 14 and the like. 17a is a flat shaft having a flat part protruding from the upper part of the shoe 17;
19 is a plate spring disposed from above the carriage 14 to the upper end of the shoe 17; 19 is a guide piece that holds the carriage 14, the plate spring 18 on the carriage 14, and the guide rail 16a;
Although it is fixed to the end of the carriage 14, it is in contact with the guide rail 16a, and the bias force of the leaf spring 17 prevents play from occurring, so that the carriage 14 slides on the guide rail 16a as the carriage 14 moves. Therefore, the carriage 14 can be moved in the direction of the arrow 20 without any hindrance.

Reference numeral 21 denotes a gear attached to the flat shaft 17a of the shoe 17 so as to be movable up and down, and the gear 21 has teeth on a part thereof and has no teeth on the other part. Reference numeral 22 denotes a gap switching lever with teeth formed on one end.
The gear 21 can be engaged with the teeth of the gear 21 using the post 23 on the top 4 as a rotational fulcrum. 24 is a platen.

To explain the operation of this configuration, first, as shown in FIG.
1 to rotate the shoe 17, and remove the carriage 14.
The printing head 13 is moved in the direction of the arrow 25 by moving one of the printing heads up and down, thereby initializing the gap between the printing head 13 and the platen 24, that is, the platen gap.

Next, the gear 21 is moved upward by the bias force of the leaf spring 18 while being fitted to the flat shaft 17a of the shoe 17, and the gear 21 and the teeth of the gap switching lever 22 are engaged with each other, and then the gear is switched. Lever 2
2 to a predetermined angle, and turn the shoe 1 together with gear 21.
By rotating 7, one of the carriages 14 can be moved upward or downward by a predetermined amount, and the print head 13 can be moved in the direction of arrow 25 to obtain the desired platen gap.

Incidentally, in the present invention, the platen gap is basically adjusted by rotating the shoe 17, and in the embodiment described above, the means for rotating the shoe 17 is by means of the gear 21 and the gap switching lever 22, but the present invention is not limited to this. Show 1, not what you want
It goes without saying that the shoe 17 may be rotated by directly fitting into the shoe 7. Furthermore, the gap switching lever 22 can be rotated manually or automatically.

Next, the means for moving the gap switching lever 22 mentioned above will be explained. Incidentally, parts that are the same as those in the above configuration are indicated by the same reference numerals, and a revised explanation will be omitted.

FIG. 4 is a perspective view showing the operating means of the gap switching lever 22, and FIG. 5 is a plan view thereof.

In the figure, 26 is a gear switching lever 22.
27 is a limiter provided at the end of the main guide shaft 15 to set the home position of the carriage 14; 28 is a side frame that supports the main guide shaft 15 and the base frame from both sides; 29 is a side frame 28 30 is its post, 31 is the bracket 29 attached to the opening of
32 is a plate cam that comes into contact with the roller 26 of the gap switching lever 22; 32a is an arcuate groove that sets the amount of rotation of the plate cam 32; 32b is a spring post of the plate cam 32; 32 is rotatably attached to the post 30 of the bracket 29, and the arc groove 3
2a through a spring post 31 to restrict rotation. 33 is the spring post 31,
32b, and always biases the plate cam 32 in one direction.

Next, to explain the operation, first turn on the power.
Then, the carriage 14 moves in the direction of arrow 34 and comes into contact with the limiter 27 in order to return to its origin. This origin finding may be detected by a sensor instead of the limiter 27. After completing the origin search in this way, position A, which is moved a predetermined amount in the direction of arrow 35, is set as the home position, and printing is performed while moving between position A and position B.

So, after setting the printing paper in the printer,
To set the platen gap appropriate to the thickness of the printing paper, the gap switching lever 22 is rotated in the direction of arrow 36 to set it as shown in FIG. Next, when the power is turned on to the printer, the carriage 14, which had been stopped at a certain position between A and B, moves in the direction of arrow 34, and the roller 26 of the gap switching lever 22 moves to the plate cam 32.
As shown in FIG.
to move the print head 25 in the direction of arrow 25 and secure the platen gap. At the same time as this movement, the carriage 14 comes into contact with the limiter 27 and completes the origin search.

In this way, after performing the platen gap and home positioning at the same time, move the carriage 14 toward the arrow 35.
It moves a predetermined amount in the direction and stops at home position A, and becomes ready for printing.

In this way, in this embodiment, the arrow 3 of the plate cam 32
The platen gap can be freely adjusted by the amount of rotation in six directions. Further, automatic setting of the plate cam 32 can be easily performed by operating a latching solenoid or the like. Then, the plate cam 32
It is also possible to facilitate operation by the operator by protruding the lever-shaped portion outside the enclosure.

[Effect of idea]

As explained above, in the present invention, a shoe is provided that contacts the guide plate and is rotatably screwed onto one side of the carriage, and by rotating the shoe, the carriage can be rotated together with the printing head around the main guide shaft. Since the platen gap is adjusted by moving the platen gap, the amount of adjustment can be made larger than that of the conventional eccentric bushing, and this has the effect of obtaining a sufficient amount of adjustment of the platen gap.

In addition, the means for rotating the shoe includes a gear that can move up and down on a flat shaft at the upper end of the shoe, a gap switching lever that meshes with the gear, and a plate cam that controls the movement of the gap switching lever. By moving the gear down to disengage it from the gear changeover lever and then rotating the shoe, you can easily initialize the platen gap, and then move the gear up to engage it with the gear changeover lever and rotate the shoe. By rotating the platen gap, it is possible to easily obtain the desired platen gap.

Furthermore, by providing means for operating the gap switching lever at the home position of the carriage, there is an effect that a desired platen gap can be automatically obtained when the carriage returns to the home position.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a side view, Figure 3 is a side view showing the initial setting of the platen gap, Figure 4 is a perspective view showing the entire shoe operation system, Figure 5 is a plan view thereof, and Figure 6 is a conventional platen gap adjustment mechanism. Plan view, No. 7
The figure is a perspective view of the eccentric bush. 13...Print head, 14...Carriage, 1
5...Main guide shaft, 16...Base frame, 16
a... Guide rail, 17... Shoe, 18... Leaf spring, 21... Gear, 22... Gap switching lever, 32... Leaf cam.

Claims (1)

[Claims for Utility Model Registration] In a platen gap adjustment mechanism for adjusting a platen gap between a print head mounted on a carriage and a platen, a guide rail is provided in parallel behind a main guide shaft arranged parallel to the platen, The front end of the carriage is slidably and rotatably attached to the main guide shaft, and a shoe having a gear at its upper end is screwed onto the carriage, and the lower end of the shoe is slidably abutted on the guide rail. The platen gap adjusting mechanism is characterized in that a gap switching lever is rotatably provided on the carriage and has teeth that mesh with the gear.